Selective relay responsive to unbalanced electric quantities



July .28, 1931'.V E, GRASSOT l1,816,675

SELECTIVE RELAY RESPONSIVE TO UNBALANCED ELECTRIC QUANTITIES y FiledAug. 15, 4192:5 e sheets-sheet 1 I/g g E91@ Fly.

o 1o 20 50 40y 50 60 70 80 9o 1o| July-28, 1931 E. GRAssoT 1,816,675

SELECTIVE RELAY RESPONSIVE TO UNBALANGED ELECTRIC QUANTTIES Filed Aug.15, 192e e sheets-sheet 2A Y Inventor;

mile Grasset,

` Hts Attorney.

July 28, 1931. E. GRASSOT 1,816,675

SELECTIVE RELAY RESPONSIVE TO UNBALANCED ELECTRIC QUANTITIES- Filed Aug.13, 1926 6 Sheets-Sheet 3 July 28, 1931. E. GRAssoT 1,816,675

I SELECPIVE RELAY RESPONSIVE TO UNBALANCED ELECTRIC QIUANTITIES FiledAug. 13,41926 e sheets-sheet 4 n; nn

6 l y A 0L' f'i July` 28, 1931. E. GRAsso'r 1,816,575

SELECTIVE RELAY RESPONSIVE T0 UNBALANCED ELECTRIC QUANTITIES Filed Aug.13, 1926 s Sheets-smetl 5 July 28, 1931, E GRASSO-r 1,816,675

SELECTIVE RELAY RESPONSIVE .TO- UNBALANCED ELECTRIC QUANTITIES UNITEDSTATES Leraars .Parnu EMILE GRASSOT, OF EEUDON, Ile"RALhT'llii,`ASSIGNOB, BY HESNE ASSIGNMENTS, TD GENERAL ELECTRIC COMPANY, ACORPORATION 0E NEW YORK SELECTI'VE RELAY RESPONSIVE TO 'UNBALANCEDELECTRIC QUAHTITIES Application led August 13, 1926, Serial No. 129,031,and in France September 19, 192e'.

Among the relays at present known, those called impedance-relays,distance-relays or relays for voltage drop, only cause a single voltageand a single current to intervene per unit of the relay. The consequenceis that in order te obtain satisfactory protection of three-phase linesit is necessary to use three relay units influenced by the threecompound or delta voltages in the case of a threelwire system, and sixelements iniiuenced by the three simple or star voltages and the threeoompound voltages in the case of a our-Wire system or with a neutral toearth. This results in complicated and costly apparatus.

Another drawback of these impedance, distance and voltage drop relayslies in the fact that, in the "forni of monophase units in which theyhave been designed up to the prese-nthit 1s necessary to use complexcurrent and voltage laws in order to have a suitable selectivity7 in theneighbourhood of the fault. These complex laws are obtained only byartifices such ns: magnetic saturation, variation in the resistance of ahot Wire, variation in apparent resistance in a circuit comprisingcapacity and self-induction varying as a function of the magnetiaingampere-turns- It ensues that these apparatus are delicate to adjust andthat it is difficult to succeed in rendering the charn acteristics ofall the apparatus on one line identical. v

The aim oi the present invention is to pro vide a simple relay forthree-phase or generally polyphase lines comprising only one unit, actedon by all the line voltages and in-I fluenced by any perturbation of thevoltage system which brought about either hy a voltage drophetvveenphases, or by a voltage drop between a phase and earth. w

The retardation in relay release: is a growing function of the perturbedvoltage and almost vanishes if this voltage vanishes.

The operation of the relay can also depend on the currents or on theirphase sequence components or again on the active, reactive or complexpower or on its phase sequence components.

Ud being the positive phase sequence component of the three-phasevoltage system, U:

the negative phase sequence component and U, the zero phase sequencecomponent or geometrical sum of thefsimple voltages, the' retardation inrelay release will, in particular, be practically proportional to one ofthe following functions:

.s 1,/ 37 I Pd-. Pd-AZ rp, p and A being constants, I d,

L, L the positive, negative and zero phase sequence components of thecurrent.

Certain of the above predetermined functions of the phase sequencecomponents of the system of voltages have been chosen owing to theirparticularly interesting orm` from the I oint of view oit selectivity.

y invention will be better understood from the following descriptionwhen considered in connection with the accompanying drawings and itsscope 'will be pointed out in the appended claims.

ln the accompanying drawings I- Fig. 1@ shows changes in voltage due toa short circuit between conductors.

Fig. lb shows the changes in voltage due to a short circuit betweenconductor and earth.

Figs, l, i, l, if, 1E, l are vector diagrams of the phase sequenceoperators as applied to the various systems described.

Figs. 2, 3, l and 5 are curves giving the the relations betweenfunctions of voltage componentsy and Hthe defective voltage expressed asa percentage of its normal value.

Figs. 6 and 7 show circuit arrangements for I obtaining componente ofvoltages and currents.l H

' Figs 8 and 9 show embodiments of circuit protectin relays.

Fig. 1s a detail view of the asynchronous motor' shown in Fig. 9. l Fig.11 is a diagrammatic-view of a relay. Fig. 12 isa circuit arrangementused 1n con'unction with the relay of Flg. 11.

i 13 and 14 are circuit arrangements for o ining components of voltagesand l. currents. g

fFigs. 15 and 16 are further embodiments 'of the invention. Fig. 17shows a circuit arrangement used with the ap aratus of Fig. 16. Fig. 1'8s ows a circuit protecting relay similar to that of Fig. 15 embodyingcertain constructional dierences.

Fi 19 and 20 show further examples of invention.

The diagrams of Fig. 1 show the cha -in the dierent voltages' in thecase of a s ortcircuit between conductors (Fig. 1") and in the case of ashort circuit between conductor and earth (Fig. 1).

For purposes of simplicity, it will be supcase of a short-circuitbetween conductor and earth the neutral point 0 remains fixed inposition, and one of the apices A of the triangle moves along thesegment A0. The point 0 is no lon r the center of gravity of thetriangle A' C and the three simple vol have a resultant. If one of thesimple vo t-v ages vanish then UF U. and

Ur=Ub In either case, the defective voltage will be taken as inde ndentvariable, reckoned as a percentage o its normal value. In the event of ashort-circuitbetween the phases B andC, the variable will then be and inthe event of a short-circuit between phaseAandearth,itwillbe -lOOXoI'Itisknownthata stemofthreeunbalaaeedvectors U1, U., canbereplaced byeircult protecting relays according to the The es y m Where ais a vectorof modulus 1 and argu ment i (see Fig. 1) Consequently a is a vector ofmodulus 1 and argument i gf or-r and a=1.

In other words a is a complex operator defined by the relationConsequently the roduct (IU1) re resents a vector of modulus 1 (U1,

1 and 1 are used to denote both the vectors and their moduli) out ofphase with respect to U1.

significance of 'the products (aU1).

or (aU.)z (aU.) can be deduced similar considerations. Fig. 1illustrates thejsystemof vectors (U1, U., U.) and the vectors (aU1) and(aU1).

If U1 U1, U, represent the voltages of a balanced three-phase systemU1+U,+U,=0, the form of the equation given under (a) and (b) canbemodiiied to aord a simple, graphlical construction.

Tlims in (1a) wfiting- (U1+U3) instead (the) {Ufer/1] Similarexpressions can be deduced for Um Hind Usd' I From Fig. 1c it will beseen that (a2-1l) represents a vector of modulus 1r *1r 2 sin 1/3 andargument-5' la] Turning now to Fig. l", let A B C be the triangle formedby the three Vectors U1, U2, U3; A B C and A B C two equilateraltriangles constructed on A B. Then IWC? will represent-#U1 and (J C willrepresent (UB-aZUl). From the expression for UG deduced above, itfollows that (UcraQ/Q is vector of modulus is a vector of modulus Bysubstituting U1`+ U3) for U2 in Equation (1b) we obtain similarlyUFm-@ZMUS-az/l) i. e. (U3-am) is a vector of modulus Ui. Now U 3-aU 1)isrepresented by C C con- The following relations between the scalar`quantities may be written down:

=U3Ul sin a (5) nowUs U1 sin 1 -*2S where is area of A A B C f. Udz--also by addition w+ Uf my U12- USUi @0S a) and by symmetry thefollowing expressions hold:

where =Ag C of A A B C w+ mega/22+ U32- U2UB COS y) wherey=BCAofAABC- Byadding up these three expressions for Udz-FU we obtain Now it followsfrom the properties/of lthe Consequently w+ U2=(U12+ 022+ van@Expression Udz-U-U as a function of the defective Voltage denoted by X.ln what follows Ui,=3]a= Ufi- Uf!h U3 @me of Fig. 1.-ln the case oil ashort circuit between conductors as illustrated in F l, 52:0 and as hasalready been shown genevieve Now v ha: ,S v where h is the constantheight of the A A B C (Fig. 1) and m is the defective voltage, in thiscase B C. Consequently This expression is proportional to and vanisheswhen a: becomes zero.

l(lane of Fig. 11h-In the case of a short eov circuit between aconductor and `earth as illustrated in Fig. l".

w=0Al and swo-aa' (Fig. 11).

. Now

2 B0 1I[h where h is the height of the equilateral triangle A B C.

This is the equation of a trated in Fig. 2. w can o y vary between O(absolute short-circuit between earth and a phase wire occurring at thespot where the relay is located) and rcase of balanced voltages).

orm assumed by Gase of Fig'. 1.For a short circuit between conductors asillustrated in Fig. 1",

Fig. l shows the vector diagram of Fig. 1' suitably modified to meet thecase, the two lequilateral triangles ABC and AIB/C being constructed onthe base BC which represents the defective voltage. Then A. A of Fig. lIcorresponds to l? of Fig. 1'.

lso A A of Fig. 1 corresponds to il" of Uf f. Ul

arabola as illus- Hence the expression is proportional to a and vanisheswhen a: becomes zero.

Oase of Fig. 1".--For a short-circuit bel tween one` of the vconductorsand earth, the

Fig. 1ll shows the modified form which the vector diagram of Fig. l'assumes. The defective voltage is now reprented by O A. In this case thezero Bhase sequence component Ur does not vanis but 1s represented by AA.

But as previously n m45. In Fig. 1', A B C is the volta. triangle andthe two equilateral triangles B C and In this case likewise theexpression is proportional to as and vanishes when w becomes zero.Consequently both in the case of a short-circuit between conductors andin the case of a short-circuit between a conductor and earth, theexpression f ZT Ur-Ur "TT when plotted against the defective voltage exressed in a percentage f its normal gli ue, -gives a straight line as jsshown in.

e curves Figs. 2, 3, 4 and 5 indicate the variations of the functionsUI- I '2 Ul-Ul-U'I U"- Uf" Uf Ui i Uri w and v Ufa-Ts' A Intherstthree',theacurvesref fer to the short-circults between conductoral and the bcurves to the short-circuits between conductor and earth.` The absci forthe a curves must be taken to represent the defective compound voltage,such as and for the b curves the defective simple voltage, such as l Itwill be seen that the curvesof Figs. 2 and 5 are practically rectilinearand that the curves of Figs. 3 and 4 are markedly concave, suchconcavity being turned towards the abscissa axis.

The release retardations, which are proportional to the ordinatesincrease in the first case in proportion to the lengths of line includedbetween the fault and the relay, and in the second and third cases theyincrease proportionately less as the length of line is longer. Hence,these two latter curves enable the selectivity of the relaysA to beconsiderably improved in the vicinity of the fault. The choice betweenthese different characteristics will evidently depend on the lineconstants.

In order to obtain the components Ud and U, circuit arrangements can beutilized similar to that of Flg. 6 in which Z1, and Z2 are impedancesequal in absolute value, but such that Z1 produces a phase displacement60 greater than that produced by Z2; A and A the circuits or apparatusthroughpwhich flow currents respectively proportional to the negativephase sequence component U., and the positive phase sequence componentUd of the voltage system.

In order to obtain a current proportional to the zero phase sequencecomponent of the .voltage Ur a circuit arrangement similar to that ofFig. 7 can be utilized, in which T1, T2, T., are three identicaltransformers and A the circuit or apparatus through which a currentproportional to U, flows.

Fig. 8 shows an embodiment of the relay, in which the components Ud, U,and Ur are utilized, 'said components being produced outside theapparatus by devices shown in Figs. 6 and 7.

An electro-magnet e1 through which Hows a current proportional to Ud ismade to act on a metallic disc d1 (Fig. 8) braked by a magnet a. Thisdisc therefore rotates at a speed proportional to Ud and in thedirectlon of the arrow f1. A yielding means such as a helical spring ris fixed at one end on the vspindle of the disc d1 and at the other endon a socket integral with the spindle of another disc d2 coaxial withthe first. The disc d2 can have a slight displacement, limited by twostops bi and b2. Three electro-magnets e2, e3 and e, act on this disc. Acurrent pro-4 portional to' Ud fiows through the electromagnet e2 whichexerts force in the direction of the arrow f. The lelectro-magnets e3and c4 have currents proportional to U; and Ulr fiowingthrough themrespectively and exert a force in the opposite direction to f. Hence thetotal torque acting on the disc d, is of value U U,U,. A. contact memberc mounted on the spindle of the disc d, can conneet togethertwo'metallic strips Z1 and 1,. When the metallic strips arer connectedtogether by the contact member c, they close a circuit containing atrip-coil T energized by an auxiliary source of current supplied by thebattery A for example. The trip-coil T 1s adapted to actuate an oil orother type of circuit breaker B which is mounted in the main circuit 1,'2, 3.y This form of rotective device is of course likewise applica le tothe other relays about to be described. The operation of the relay is asfollows: Ud being always greater than or at least e uall to U-i-U', theresultant torque on t e disc d2 has always the same sign, and is alwaysin the direction f. lThis torque tends to separate the contact c fromthe strips l1 and l, and to press the movable equipment against the stopb1. If a fault occurs at instant() (zero), the disc d1 immediatelystarts to rotate. An auxiliary device only permits this motion when thefault occurs, and brings the disc back if the fault ceases. When thedisc d1 starts rotating the spring' 1r tends to rotate the discd2towards the contact. This rotation is brought about when the springtorque overcomes the total torque of the electromagnets, e2, (3 e, whichis exerted in the oposite direction. Consequently the disc d, 1ssubjected to two `,counteracting turques, namely the torque Ud Ul U.produced by the electromagnets e2; es, e, and a torque Kg transmitted bythe sgrin 1', proportional to the angle of. twist d o the spring. Forequilibrium U42- Ugz* Ufz=K v Uf- Ufflughaf- (w- U.'- Um.

msA

Assuming (uf-Ua-U) isnegngibie in comparison ,with Ud ff U- Ua. Uf

K U4 i. e. the relay release retardation is proportional to Ud: ma UfaUf The resolution of the voltage system into its symmetrical elementscan be avoided. In particular, torques proportional to UdLl-Ul andUlf-U12 can be obtained in the relay.

Fig. 9 shows a device based on this consideration.

In the relay shown in Fig. 9 the motor system is constltuted by ametallic disc d, on which three electro-magnets el, ez, e, act andthrough which three currents proportional to the three delta or compoundvoltages flow respectively andthe total torque exerted on the disc isgiven by a The bell t is keyed on a spindle It (Fig. 9). A disc d2 actedon by an electro-magnet e, through which iows a current'proportional tothe zero phase sequence component of the l voltage is keyed on the samespindle. The torque exerted on the bell is in the direction f and thetorque exerted on the disc d, is in the opposite direction. The totalAtorque on the spindle h is therefore of value.

The disc Z1 is braked by a magnet a'and is connected to the spindlehthrough a spring r, as in the apparatus described-above. The operationis the same and the relay release retardation is proportional to Inorder that the disc d1 shall only be set in motion at the moment when afault occurs,

and in order to bring-the disc back when the fault ceases, the followingdevices shown diagrammatically in Figs. 11 and 12 are made luse of.Through three coils b1, b', b' located the three currents of the line tobe protected. l

A movable armature a controlled by a spring 1, is attracted if one ofthe currents exceeds a xed value. This armature establishes a system ofthree contacts c1, c2, c, (Fig. 12). The electro-magnets e1, e2, e8,which act on the disc d1 include two windings el, e1 for theelectro-magnet e1, e e, for the electro-magnet e2 and e., ea for theelectro-m et e.. The windings e1,c2,e are connecte across the compoundvoltage, reduced to a suitable value, for example, by transforming meansT1, T2, T3, as shown, and the windings e 1, e2, es are connected at oneof their ends to the middle points of the windings e1, e, e', and at theother ends to one or other of the outlets of the windings @'1, ez, e',according to the position of the contacts 01,02, 0 i. e. of the movablearmature a. This inversion of the windin e"1, e e. enables the directionof rotatlon of the disc d1 to be changed;

The operation of the relay is then as follows: As long as a fault hasnot occurred in the installation, the line currents have a moderatevalue; the armature a is not attracted and the contacts c1, cz, c, arein such a position that the disc d, has a tendency to rotate in the oposite direction to that of the arrow f1. he stop b, limits its motion.When a fault occurs there is simultaneous. drop in voltage and rise incurrent. The armature a is attracted, the contacts c1, c2, c, assumeanother position which corresponds to the rotation of the disc d1 in thedirection f1. The spring r is then wound up or stressed until its eifectovercomes that of the coils '111, 11 v, and the contact c connects thestrips Z1 and 1,.

Fig. 13 is an assembl wiring diagram of the connections of a re ayaccording to the invention. T1, T2, T, are three voltage transformersthe primaries of which are mounted in star connection between theconductors and earth. e1, e e, are the simplified windings of the motorequipment. fvl, vz, fu, are the windings of the three-phase asynchronousmotor. T.l is an auxilia transformer intended to totalize the simplevoltages in order to deliver to the windlng e,L a current proportionalto thezero phase sequence component of voltage. The windings e1, e2, e.,v1, 12 v. are connected across the dierences between the sim le voltagestaken two at a time in cyclic ordbr. Hence currents proportional to thecompound voltages flow through them.

If the disc d1 were replaced by a constant speed motor such as a cockwork motion, an

system of voltaves or currents.

i as

induction motor with practically constant speed or the like,obviousl'yjthe timeof release would be proportional toUdz-U.-

r.. The use of three-phase circuit arrangements permits of importantsimplifications in the design of relays. Thus in orderl to obtain atorque proportional to (Udz-i-U), Ud being the positive phase sequencecomponent and U1 the negative phase sequence component of the system ofvoltages, it is sutlicient to use two electro-magnets in place of thethree electro-magnets of the threephase system. In order to obtain atorque proportional to. (Uf-U12) an electro-magnet with two windingssimilar to those of induction meters can'be used in a two-phase system,currents proportional to the two twophase voltages fiowing through thesewindi ings. This device replaces the three-phase asynchronous motor ofthe opposing equipment of Fig. 9.

Moreover, wit-h the Scott device, with 'l circuit arrangements, etc. athrce-phase system of voltages or currents can be easilytransformed'into a two-phase system, the symmetrical components of whichare proportional to those of the three-phase system.

It is even possible to obtain directly a symmetrical two-phase systemeither positive or negative starting from the given tiree-phasc Fig. 14is a wiring diagram of a relay similar to that of Fig. 9, the wiring `ofthe relay being partially carried outftwo-phase and.y the two-phasevoltages beingobtairied by a.; Scott circuit arrangement fed "by" thethree-k phase voltages of the circuit to be protected..

Fig. 15 is a general view of the relay.l In Fig. 14, N, 1, 2, 3,represent the four conductors of the circuit (N can also-represent theearth in the case oflinesl with'three conductors and earthed neutral)T1, T2, T,

1 the windings of two other electro-magnets e1 and e2. These latterproduce the torque proportional to (UdLtUiz) whilst the electro- Inagnet@'3 23 produces the torque proportional to (UGL-Uf) which may beobtained by the vector product of the delta Voltage and. the medianvoltage which is in quadrature thereto under balanced conditions. Forthis purpose the power factors of the two parts ea, 0., of theelectro-magnet e3 should be substantially the same. The 'electro-magnete.,

produces the torque proportional to the square of the zero phasesequence component of the voltage. This latter electro-magnet isunnecessary as also are the transformers which feed it, if the linehas"three conductors without earthed neutral.

i Fig. 15 shows an embodiment of the relay the wiring diagram of whichis indicated in Fig. 14. In Fig. 15, d1 denotes a metallic disc on whichact two electro-magnets e1 and 4e2 respectively subjected to thetwotwo-phase voltages V2.3 and Vm. This disc can rotate in the directionflif a fault occurs and in the opposite direction when the fault hasceased. The change in direction of rotation can take place by means of adevice similar to that mentioned above. The disc d.: is retarded by amagnet a. A spring ris ixedfat one end to the spindle of the disc d1 andat the other end to the spindle of a second disc d2, on which twoelectro-magnets`e 3 and e,l act. Through the winding e', of theelectro-magnet e3 there Hows a current proportional to one of thetwo-phase voltages such as V2.3 and through the winding e, a currentproportional to the other two-phase voltage such as Vm. The torque ofthis electro-magnet is exerted in the direction f2. Through theelectro-magnet c., flows a current proportional to the zero phasesequence component Ur of the voltage (geometrical sum of the simplevoltages) and its torque is exertedin the opposite direction to f2. Twostops b1 and b2 limit the movement of the disc d2. A contact member ccan connect two metallic strips ll and Z2, thereby causing the operationof a circuit breaker.

Fig. 16 shows diagrammatically another embodiment of a relay accordingto my in'- vention.

A metallic disc d, braked by a magnet a is subjected to the action oftwo electro-magnets through which two currents proportional to I., andI, flow respectively. The electro-magnet through which the current I,flows need alone be retained if the possibility .of a symmetrical faultis not taken into con- 'IISk three magnetic cores subjected to theaction of three solenoids through which currents proportional to Ud, U,and Ur flow respectively.- The coil acted on by Ud exerts a downwardattraction and the other two exert an upward attraction. Matters arearranged so that the attractions produced by the three coils arerespectively proportional to Ud, U, and

` The tot-:.1 force in the downward direction is thus proportional to(Ua-'UV- w/Ul.

The contact c closes when the disc d has rotated through a suiiicientangle for the spring r- .to overcome the attraction of the solenoids.

The voltages Ud and U1 alon with the currents Id and 4I1 can be obtaineby known circuit arrangements.

It is not necessary to obtain exactly the function Uf (Ua- U4 It couldbe taken proportional to (Idz-i-Il) which is easily obtainable byconversion to two-phase. In Fig. 17 is shown a two-phase circuitarrangement for the electro-magnets acting on the lower disc of Fig. 16.Thron h one of the electro-magnets the current gl, fiows and through thetwo windin of the other the currents I1 and I2 so t at theirampere-turns are in opposition. By suitably regulating the number-ofcoil turns, a symmetrical two-phase system of ampereturns is obtainedfor a balanced system of currents I1, I2, L.

In the preceding devices the line current was utilized as one of thecharacteristic elements of the fault. t

Now a relay can be designed which in no way depends on line currents,and which produces selectivity solely by making use of voltagedistortiom, For this purpose the opposing unit'of the relay beingsimilar to those already described, its motor element is subjected tothe action of the line voltages or to the action of a function of theirsymmetrical components such that the force exerted on this equipment isa maximum in the vicinity of the fault.

An electro-magnet which is subjected to the negative phase sequencecomponents U, of the voltage system can be made to act on the movablerelay equipment. An opposing spring will maintain the movable relayequipment against the stop below a certain value of Ui. In theneighborhood of the fault, the term U, will become important and themovable equipment will start rotating. In

order to preserve the sensitivity of the relay in the event of a shortcircuit between conductor and earth therecan be added an electro-magnetinfluenced by the voltage Ur.

The spring for bringing back the movable equipment into position may bedispensed with by causing a system of electro-magnets to act on saidmovable uipment, the electromagnets are so combind that, if the voltagesbeing balanced, there is a tendency for the movable equipment to rotatein the backwards direction and if the want of balance of the voltagesincreases beyond a certain value, it has a tendency to rotate in theother direction, that is to say,` in that direction which can bringabout they release vof the circuit-breaker.

As an example, two methods of realizing the present device will bedescribed, one in which the line voltages are used directly, the otherin which their s mmetrical components obtained by known circuitarrangements are used.

In the first method, the system of threephase voltages may first betransformed into a two-phase system, for the purpose of simplifying theapparatus.

The relay motor equipment comprises a metallic disc on which threeelectro-magnets y act. One electro-magnet includes two windings through-which two currents flow re- .spectively proportional to the twotwo-phase voltages and produces a torqueon the disc:

1=K1 (Udz- U42) Ud and Ui being the symmetrical positive and negativephase sequence components of the vo The two other electro-magnets areinfluenced, one by one of the two-phase voltages and the other bytheother two-phase voltage and the total torque of these twoelectro-magnets can be written:

Uzr-Kz (Ugz'i-Uiz). Matters are arranged so that C1 and C2 are ofcontrary sign, C2 acting in the direction which produces the relayrelease, and C1 acting in the op osite direction. It is easy to see thatthe disc is under th iniuence of no torque if The disc is prevented fromAmoving if and it turns in the direc-tion of release if The op singrelay equi ment can be constitute as has been descri in the first partof tho present specification.

One of the constants K1 or K, can be made to vary by any means whatever.

For exvalue of K1 will correspond and hence a4 value of e above whichthe relay can start operating. Another electro-magnet can vbe added tothe above three mentioned electromagnets through which flows acurrentproportional to the zero phase sequence component Ur of thevoltage in order preserve the same operation for the relay in the eventof voltage drop between two conductors and in case of voltage dropbetween conductor and earth. Y

In the second embodiment two electro-magnets are caused to act. on themetallic disc of the motor equipment which electro-magnets arerespectively subjected to the action of the direct and inversecomponents of the voltage system. Theelectro-magnet acted on by U1 willexert its torque in the direction of release and the electro-magnetinfluenced by Ud will exert its torque in the opposite direction. Underthese conditions, matters may be arranged so that, if the voltages arebalanced, the electro-magnet under the influence of Ud will overcome theeffect of the other and if the want of balance of the voltages exceeds acertain value, the electro-magnet acted on by U, will overcome the otherand thus produce the relay release.

A third electro-magnet acted on by Ur which exerts its torque in thekdirection producing relay release can be also added to these twoelectro-magnets.

In numerous cases, it may be of interest to obtain a selective relay forunbalanced voltages, the operation of which depends on the direction ofpower feedingI the fault. The problem arises in particular in lines fedat their two extremities and in lines in parallel. In this case, theselective relay according to the invention can be designed in a mannerdiffering slightly as follows.

The relay motor equipment is subjected to the action of anelectro-magnet influenced by the negative phase sequence component Ui ofthe voltage and by the negative phase sequence component I, of thecurrent so as to obtain a torque of the form 0=K Ui I@ c os (oV-a),

will be preferably subjecte to a torque of cality is suc 'that the motorequipment torque is exerted in the opposite direction to that which mustproduce release, this equipment will remain against its sto and therelay will not operate. If the fault ocality is such that the motorequipment torque is exerted in the direction which produces release, themotor equipment will start rotating and the relay will be released afteran interval which depends'both on the symmetrical voltage and currentcomponents and which can be eX- pressed in the form:

-Moreover, in certain cases the relay might. only include part of theelements shown in I the drawings or in thef-,descriptions. Thus, in thethree-phase lines-with three conductors without earthed neutral, theparts of the relay utilized for protection against short circuitsbetween conductor and earth may be omitted. Similarly, if the relay onlyserves for the protection of a circuit against the fault of earthing,the elements affording protection against contact between conductors maybe omitted. The relay forming the object of the invention may serve forthe protection of two-phase, or in general polyphase circuits. will beadaptedI for each case. Thus, 1n twophase lines with three or fourconductors, a two-phasecircuit arrangement will be preferably employed,for example, that of F ig.

vl5, the electro-magnet e4 being suppressed.

In the case of a five-conductor two-phase line, the electro-magnet e4will be retained and it will be fed by the zero phase sequence voltagecomponent of the circuit.

Fig. 18 shows a form of relay similar to that of Fig. 15 but differingtherefrom by interesting details of construction. A metallic disc d1mounted between two bearings p1 is subjected to the action of anelectroma-gnet e1 and braked by a magnet a. The two bearings` p1 aresecured to a frame b which can pivot about pivots p1. This frame b canhave a rocking motion of small amplitude, limited by two stops not shownin the drawings. A spring 1" brings the frame back against one of thestops. When the force developed by the electro-magnet the form:meuf-Uf); mh@ man.

The circuit arrangement e1 is suliicient, the frame b rocks and thetangent screw or worm v engages with the toothed wheel or worm gear s,thus transmitting the rotational motion of the dlsc d1 to the spindlez'. A spiral spring j 1s fastened at one end to a plug secured to thespindle z and at the other end to a lever Z secured tothe spindle m ofthe second equipment which includes a metallic` disc d2 and a contactmember k2. The disc d2 is pivoted between two bearings p2 and issubjected to the action of two electro-magnets e2 and en'.

The electro-magnet e1 produces on the disc d1 a torque proportional to asuitable value, such as dthe ne ative phase sequence voltage componenti, the negative phase 5 sequence current component Il, the ne ativephase sequence power component Ur i cos qb., the reactive negative phaseuence component of the power U, I, sin 4a, t e complex negative phasesequence component of the power .Ui L cos (4:1 01), where a is aconstant, the zero phase sequence com onent of the wer U., the earthcurrent i, the power r I., cos e0, etc. The electromagnets e2 es producetogether on the disc d2 a torque proportional to U-U-*Ur for example.The operation of the relay is .similar to that of the apparatus alreadymentioned with the difference that the disc ci1 can start rotatingbefore the factor acting on the electro-magnet e1 has acquired thenecessary value for producing engagement of the worm o and the worm gears. A contact itl which closes at the instant of engagement is providedto be connected in series with the principal contact k, in order toavoid the release of the circuit-breaker due to an accidentaldisplacement of the disc d2. The spring r can be adjusted, so thatengagement is brought about for a given value of the torque acting onthe electro-magnet el. The magnet a can also be adjusted, so as to eadapt the timing of one group of rela with the line characteristicswhich they ave to protect.

Other mechanical means are known enabling a relay member to be releasedafter a Y lapse of time proportional to the quotient of two functions. tis known for example, that the release retardation of any timed re- Alayis proportional to the uotient of the travel it must accomplish be oregi contct and its s supposed uniform iiuring itsmotion. t is thereforesucient to royide a movable equipment the speed of w 'ch is proportionalto the function in the de nominator and to vary the travel of thisequipment in proportion to the function in the numerator. y Y

Fig. 19 shows anembodiment of such a reznconformance with the invention.The e y retardation'is proportional to Ua- Uf', V 11i A. In Fig. 19, T1and T, are two vol ormers comprising a secondary S1 and formersrespectively ffeed the two e, and e, of an electro- E. This elec- 0tro-magnet acts on a vdisc d brahed-bytwo nets a and controlled by aspring r. e torque of the electro-magnet is exerted in the direction fand is proportional to UUf. The disc takes upa position of equilibriumfor each value of the function group. S, of these trans- Ud- U A pinionp keyed on the spindle of the disc d gears with a rack c and transmitsthe motion of the disc to a rod t which can move through two guides. Asecond disc d is subjectedV to the action of an electromagnet E', thetwo windings e'1 and e', of which are connected in parallel, a currentproportional to the negative phase sequence' component L of the systemof currents flowing through each of them.

The disc d is braked by two magnets a and is controlled by a spring r.The disc d is cut out according to a law so that when it has started torotate under the influence of an inverse current exceeding a givenvalue, its motion continues in a uniform manner. This motion istransmitted lthrough the agency of a pinion p and a rack c to a rod twhich can move in two guides. Two contact members K and K respectivelyborne by the rods t and t cause 'by their encounter the operation of thecircuit breaker which is controlled by the relay. The speed of the discd' is proportional to L and the distance it must move through beforecontact is roportional to the angle of rotation of t e disc d. Itfollows that the encounter of the contact members K and K' occurs with aretardation proportional to Another method of obtaining a retardationproportional to the quotient o two functions consists in making use of amovable constant speed equipment and in va the travel t at thisequipment must m e fore causing a control contact, proportionally to thequotient of the two functions under consideration. Fi 20 shows anembodiment of such a relay, t e release retardation of which isproportional to Ua Ua.

directions on the disc which is cut out to such lli a shape that ittakes up a position of equlibrium depending only on the ratio Calling athe it will, for examp e, be taken that ifa-Kamm@ deviation .sa nu limle of deviation offthe disc angles are reckoned from this maximumdeviation we have:

A Contact 'member C1 is mounted onthe spindle of the disc d which may beretarded by drag magnets, not shown in the drawings. A second constantspeed movable equipment comprises a spindle a pivoted'at its lowerextremity in a foot-bearing C, which also serves as upper bearing forthe s indle of the disc d. The spindle a is guided) at its up er end ina bearing P. This bearing is pivotally mounted in a stirrup e secured toa ma eti'c armature A and acted on by a spring A constant speed motor Mcan engage by means of its tangent screw or worm c with a toothed pinionor worin gear p keyed on the spindle a. The engagement of the pinion pis brought about by a slight displacement of the stirrup @when thearmature A is attracted by an electro-magnet E3 having three coils B1,B2, B3 respectively excited by three currents proportional to the linecurrents. A contact member c2 is secured to the spindle a and a spring ropposes the motion transmitted by the screw if.

The operation of the relay is as Jfollows. When the protected line is innormal condition, the line currents have only a moderate value and thearmature A is not attracted by the electro-magnet E3. .The pinion p isdeclutclied from the motor M and the spring r brings the upper equipmentagainst a stop not shown. ln case of fault on the line, tlie currentsincrease, the armature A is attracted and the pinion p engages with themotor M which sets it in motion in the direction of the arrow withuniform speed. After a time proportional to the angle through which thedisc d has turned, the contact C2 meets the contact C1 tlius bringingabout the operation of the circuit breaker. v

l. Polypliase circuit protecting and timing apparatus including tworelatively movvable equipments, means enabling one equipment to act onthe other and means' for causing torques dependent on dilierentApredetermined functions of the phase sequence components of the circuitto be protected to act on said. equipments, .QL Polyphase circuitvprotecting and timing apparatus including two relatively movableequipments, means enabling one equipment to act on the other and meansfor causing torques dependent on different predetermined functions ofthephase' sequence components of the circuit to be protected to act on saidequipments, said torques acting in opposition on said equipments.

3. Protecting and timing apparatus for av polypliasc circuit includingtwo relatively movable equipments, meansV enabling one uipment to exerta driving force on lthe ot er, means for causing torques dependent ondifferent predetermined functionsof the phase sequence components of thecircuit to e protected to act in opposition on said equipmentsrespectively and means on said other equipment for controllingsaidcircuit.

4. Polyphase circuit protecting and timing apparatus including tworelatively movable. equipments, yielding meansl enabling one equipmentto exert a driving force on the other, means for causing torquesdependent on different predetermined functions of the phase sequencecomponents of the circuit to e protected to act in opposition on saidequipments respectively.

5. Protecting apparatus for a polyphase circuit includin two relativelymovable equipments, resilient means for enabling one equipment to exert,a driving torque on the other, means for causing torques dependent ondifferent predetermined functions of the phase sequence components ofthe circuit to be protected to act on said equipments, said torquesacting in opposition on said equipments and means on said otherequipment for controlling said circuit.

6. Protecting and timing apparatus for a polyphase circuit including tworelatively movable equipments, means enabling one equipment to exerty adriving torque on the other, means for causing torques dependent on'different predetermined functions ot the phase sequence components ofthe circuit to be'protected to act in opposition on said equipmentsrespectively, means on said other equipment for controlling said circuitand devices for effecting the energization of one on dilierentpredetermined functions of the phase sequence components of an electricquantity of the circuit to be protected to act in opposition on saidequipments respectively, means in said other equipment for controllingsaid circuit and devices for causing said driving equipment to move onlywhen a fault occurs on t e circuit.

8. Protecting and timing apparatus tor a polyphase circuit including tworelatively movable equipments, means enabling one equipment to exert adriving torque on the other, means for causing torques dependent ondifferent predetermined functions of the phase se uence' components ofthe circuit to be protecte to act in opposition on said equipmentsrespectively, controlling means in said other equipment for effectingthe opening of said circuit, and devicesfor causing said `69 and of thesquare of a zero phase sequence driving equipment to move in a directionto exert a torque on said other equipment only when a fault occurs onthe circuit, said devices being arranged to move the driving member inthe opposite direction to its original pition when the fault ceases.

9. Protecting and timing apparatus for a polyphase circuit including tworelatively movable equipments, resilient means enabling one equipment toexert a driving ,torque on the other, means for causing torquesdependent on different predetermined functions of the phase sequencecomponents of an electric quantity of the circuits to be protected toact in opposition on said equipments respectively, said one e uipmentbeing retarded and arranged to drive said other equipment when thevtorque acting on said one equipment overcomes the torque acting inopposition on said other equipment, controlling means on said otherequipment for eii'ecting the opening of said circuit, said controllingmeans becoming operative when said other equipment is displaced.

10. Protecting and timing apparatus for a polyphase circuit includingtwo relatively movable equipments, yielding means enabling one equipmentto exert a driving torque on the other, circuit arrangements forobtaining phase sequence components of the circuit to be protected,means for causing torque dependent on diierent predetermined functionsof said components to act in opposition on said equipments andcontrolling means on said other equipment for ef fecting the opening ofsaidcircuit when said other equipment is displaced.

11. Polyphase circuit protecting apparatus, including a motor equipmentand an opposing equipment, means for causing a torque 1mctional of atleast one of the phase sequence voltage components of the circuit to beprotected to act on said motor equi ment, and means for causin a torquefunctional of the square of a posi ve phase sequence voltage component,ofthe square of a negative phase sequence voltage component and of thesquare of a zero phase sequence voltage component to act on saidopposing equipment.

12. Polyphase c1rcuit protecting and timing apparatus, including aretarded motor equipment and an opposmg equipment, means for causing atorque unctionalof at least one of the phase sequence components ofthecircuit to be protected to act on said motor equipment, and means forcausinga torque functional of the square of a positive phase sequencevoltage component, of the square of a negative phase sequence voltagecomponent voltage component to act on said opposing equipment, saidtorques acting in opposition to each other--f' 13. Polyphase timingapparatus," including a motor equipcircuit protecting and ment and anopposing equipment, means for causing a torque functional of at leastone of the phase sequence voltage components of the circuit to beprotected to act on said motor equipment, and means for causing a torquel:functional of the square of a positive phase sequence voltagecomponent, oi the muare of a negative phase sequence voltage componentand of the square of a zero phase sequence voltage component to act onsaidl opposing equipment, and a mechanical connection between said twoequipments.

14. Polyphase circuit protecting and timing apparatus, including a motorequipment and an opposing equipment, means for causing a torquefunctional of at least one of the phase sequence voltage components 'ofthe circuit to be protected to act on said motor equipment, and meansfor causin a torque functional of the square of a positive phasesequence voltage component, o the square of a negative phase sequencevoltage component and of the square of a zero phase sequence voltagecomponent to act on said opposing equipment, and a mechanical flexibleconnection between said two e uipments.

15. Polyphase circuit protecting and timing apparatus, including aretarded motor equipment and an opposing equipment, means for causing atorque functional of at least one of the phase sequence voltagecomponents of the circuit to be protected to act on said motorequipment, and means for causing l a torque functional of the squares ofat least two of the phase sequence volta e components of the circuit toact on sai opposing equipment said torques actin in opposition to eachother, and a mechanica connection between said two equipments.

16. Polyphase clrcuit protecting and timing apparatus, including a motorequipment and an opposing equipment, means for causing a torquefunctional of at least one of the phase sequence voltage components ofthe circuit to be protected to act on said motor equipment, and meansfor causing a torque functional of the squares of at least'two of thephase sequence voltage components of the circuit to act on said opposingequipment said torques acting in opposition to each other, and a me-`chanical flexible connection between said two equipments.

17. Polyphase circuit protecting and timing apparatus including amotorequipment and an opposing equipment, means for causing atorquefunctional of at least one of the phase -sequence voltage components ofthe circuit to,v be protected to act on said motor equipment, andmeans'for causing a torque. proportional to the difference between thesquare of a positive phase sequence voltage component and the sum of thesquares of the 4negative and the zero phase sequence v oltage componentsto act on said opposing equipment.

coaxial with the spindle of said first men' tioned disc, a spring memberconnecting said coaxial spindles, electro-magnetic means for exerting onsaid second mentioned disc a torque opposed to the torque on said iirstmentioned disc and proportional to the difference vbetween the square ofa positive phase seuence voltage component ofthe circuit and t e sum ofthe squares of the positive and I the negative phase sequencey voltagecomponents of the circuit, a contact member mounted on said secondmentioned spindle, said contact member effecting the opening of saidlswitch when the torque exerted by said spring on said second mentioneddisc overcomes the opposin torque exerted on said second mentioned disc,and stops.to limit the rotation of said second mentioned disc.

i9. Threephase circuit protecting and timing apparatus, including incombination a rotatable disc mounted on' a spindle on said disc, atorque proportional to the sum of the squares of the positive andnegative phase s uence voltage components of the circuit to protected,means for retarding the speed of said disc, a shaft coaxial with saidspindle, electro-magnetic means for exerting on said shaft a torqueopposing the torque on said disc and being proportional to thedifferencebetween the square of a positive phase sequence voltagecomponent of the circuit to be protected and the sum of the squares ofthe negative and zero phase sequence voltage components, resilientconnecting means between said spindle and said shaft, a contact memberon said shaft and means for limiting the rotation of said shaft.

20. Polyphase circuit protecting apparatus including in combination twomovable equipments, relatively movable contacts controlled by said.equipments, means for subjecting said equipments to torques functionalof phase sequence components of the circuit to be protected, meansforfcausing one equipment to rotate at substantially constant speed whena fault occurs in said system and means for causing said other equipmentto take a position of. equilibrium, said Aposition of e uilibrium,regulating the distance-through w ich one of said contact members mustmove before contact takes place.

2l. Polyphase circuit protecting a paratus including in combination arotataeledislz `cooperating means mounted on a spindle, electromagneticmeans for exerting on said disk a torque de endent on a predeterminedfunction of a urality of the phase'se uence components oian electricquantity o the circuit to be protected, means for retarding said disk,means tending to brin said disk-back to an initial position, a movablemember, a resilient connection between said spindle and said movablemember, .7

effect dependent on a predetermined function of a plurality of the phases uence components of an electric quantity o a circuit, cooperatingmeans for exerting an eect dependent on at least one of the phasesequence components of an electric quantit of the circuit and meanscontrolled by ytl7e conjoint action of said exerting means.

23. In combination, means for exerting an effect dependent on a,function of at least two of the phase sequence components of van elec,-tric quantity of a circuit, cooperating means for exerting an effectdependentl on a function of at least onel of the phase sequencecomponents of an electric quantity of the circuit and means controlledbyv the conjoint action ofysaid exerting means in accordance with aresultant of the effects exerted thereby.

24. In combination, means for exerting a force dependent on apredetermined function of at least two of the phase sequence componentsof an electric uantity of a circuit and (ior exerting a force dependenton a diii'erent predetermined function of said two phase sequencecomponents of said electric quantity and means controlled conjointly bysaid force exerting means in accordance with one of the phase sequencecomponents of said electric quantity.

25. An electro-responsive device including rotatably mounted inductiondisc means and electro-magnetic means for exerting thereon a torquedependent on the difference between two ditferent predeterminedfunctions of the phase sequence components of an electric quantity of acircuit.

26. In combination, two relatively movable members, means for exertingon one of said members a force dependent on the sum of the squares ofthe positive and negative'pliase sequence components of an electricquantity of a polyphase circuit and means for exerting on the othermember a force dependent on the difference between the squares of saidphase sequence components, and means controlled by the conjoint actionof said movable members.

27. In combination, a retarded movable member, means for exertingthereon a force dependent on the sum of the squares of the positiveandnegative phase sequence components of an elect-ric quantity of apolyphase circuit, a relatively movable member, means for exertingthereon a force dependent on the difference between the squares of saidphase sequence components and means controlled by the relative movementof said movable members.

.28. The combination of relatively movable members and means Aforcontrolling the relative movement thereof including means for exertin aforce dependent on a redetermined inction. of a plurality of t e phasesequence vcomponents of an electric quantity of a circuit andcooperating means for exerting a force dependent on at least one of thephase sequence components of an electric quaiitip1 of the circuit. v

29. e combination of relativel movvable members and means for contro ingthe relativeV movement thereof including means for exerting a forcedependent on a predetermined function of a plurality of phase sequencecomponents of an electric quantity of a circuit and cooperating timeelement means for exerting a torque dependent on a differentpredetermined function of a plurality of the phase sequence componentsof an electric quanti of the circuit.

30. In combination, relatively4 movable members, means for controllingthe relative movement thereof in accordance with the dif-y ferencebetween the sum of and the diierence between the squares of the positiveand negative phase sequence components of an electric arranged to exerta force Adepen ent on a dierent predetermined function of the phasesequence components of said circuit.

32. Protective apparatus for a polyphase electric circuit including tworelatively movable members, means for retarding the movement of one ofsaid members, means for controlling the relative movement of the membersincluding means for exerting' on the retarded member a force dependenton a predetermined function of the phase uence components of an electricquantity of t e circuit to be rotected, means for exerting a force .onsaid other member, and means responsive to an abnormal condition of thecircuit for changing the direction of the force exerted on one of saidmembers.

33. Protective apparatus for a polyphase electric circuit including tworelativel movrelativeY movement thereof including means for exerting onone of said members a force dependent on a predetermined function of thephase sequence components of an electric uantity of the circuit to beprotected, means for changing the eiect of one of said phase sequencecomponents on said one of said members including means for exerting onthe other member a force dependent on a different predetermined functionof the phase sequence components of an electric quantity of the circuit,and means for controlling the starting and for insuring a rapid reset ofthe second movable member. v

EMILE GRASSOT.

able members and means for controlling the

